<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0,maximum-scale=1,minimum-scale=1,user-scalable=no">
  <title>index.html</title>
</head>

<body>
  <div class="box">
    box
    <div class="son">son
      <div class="son2">son2</div>
    </div>
  </div>
</body>

</html>